|Rank|Wrestler|No. of reigns|Combined defenses|Combined days|
|---|---|---|---|---|
|1|Keiji Mutoh|4|19|1,238|
|2|Hiroshi Tanahashi|6|27|1,237|
|3|Shinya Hashimoto|3|20|1,052|
|4|Tatsumi Fujinami|6|13|785|
|5|Kensuke Sasaki|5|9|647|
|6|Yuji Nagata|2|12|570|
|7|Kazuchika Okada†|2|10|556+|
|8|Kazuyuki Fujita|3|3|478|
|9|Big Van Vader|3|4|451|
|10|Shinsuke Nakamura|3|9|390|
|11|Riki Chōshū|3|5|383|
|12|Antonio Inoki|1|4|325|
|13|Brock Lesnar|1|3|280|
|14|Hiroyoshi Tenzan|4|2|197|
|15|Yoshihiro Takayama|1|3|185|
|16|Satoshi Kojima|2|2|168|
|17|Togi Makabe|1|3|161|
|18|Scott Norton|2|4|126|
|19|Nobuhiko Takada|1|1|116|
|20|Bob Sapp|1|1|66|
|21|Salman Hashimikov|1|0|48|
|21|Tadao Yasuda|1|1|48|
|23|Manabu Nakanishi|1|0|45|
|24|Masahiro Chono|1|0|44|
|25|Genichiro Tenryu|1|0|25|

Question: what is the difference in combined defenses between hiroshi tanahashi and kensuke sasaki?
Answer: 18